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Tempo and mode in sloth body size evolution
Article
Authorship:
Boscaini Alberto ; Casali, D.M. ; Toledo, N. ; Cantalapiedra, J.L. ; Bargo, M.S. ; De Iuliis, G. ; Gaudin, T.J. ; Langer, M.C. ; Narducci, R. ; Pujos, F. ; SOTO, EDUARDO MARIA ; Vizcaíno, S.F. ; SOTO, EDUARDO MARIADate:
2025Publishing House and Editing Place:
AMER ASSOC ADVANCEMENT SCIENCEMagazine:
SCIENCE AMER ASSOC ADVANCEMENT SCIENCESummary *
The recurrent emergence of multi-tonne herbivores is an outstanding aspect of the Cenozoic mammal radiation1,2. Most of these giants have vanished over the last 130,000 years3, critically compromising several ecosystem functions4–6. However, we still need a proper understanding of the timing and macroevolutionary processes behind the rise and collapse of some of these lineages7,8. This is true for the giant sloths, among the largest mammals ever to roam the Americas9,10. Using phylogenetic methods based on total-evidence evolutionary trees and comprehensive body size estimates for extinct sloths, we show that their size evolved in association with major transitions in lifestyle, and that terrestrial lineages achieved the largest sizes via slower rates of evolution compared to arboreal forms. Sloth size disparity increased during the late Cenozoic climatic cooling, likely following the expansion of more heterogeneous, savanna-like landscapes. Palaeoclimatic changes, however, do not account for the rapid extinction of ground (terrestrial and semiarboreal) sloths, beginning approximately 15,000 years ago. Their abrupt demise implies a role for humans as a driving force in the decline and extinction of ground sloth species. Information provided by the agent in SIGEVAKey Words
BODY SIZESLOTHMACROEVOLUTION